Adjustable sundial



May 1, 1962 E. (5. JEWETT 3,031,763

ADJUSTABLE SUNDIAL Filed May 12, 1960 3 Sheets-Sheet 1 May 1, 1962 E. G. JEWETT ADJUSTABLE SUNDIAL s Sheets-Sheet 3 Filed May 12, 1960 M I INVENTOR {M6 9% K m .MA

United States Patent Ofiice 3,031,763 ADJUSTABLE SUNEEHAL Edmund Gale Jewett, to Spring St, South N orwallr, Qonn.

Filed May 12, 19nd, Ser. No. 28,621 8 (llainls, (Cl. 33-452) This invention relates to a Sundial, and has for an object to provide a sundial which is of simple construction and is more accurate than sundials now generally available.

It is also an object to provide such a sundial which may be easily adjusted to show local clock time.

Another object is to provide a sundial which, instead of using the shadow of an opaque object to indicate the time, uses a narrow beam of sunlight falling on a dial face suitably calibrated to indicate the hours of the day by the position of this beam of light.

A further object is to provide a Sundial which may be readily used in a south window of homes or schools, as well as may be readily adapted for an outdoor type of sundial, with means whereby it may be readily and accurately oriented in proper position with relation to the earths axis and the plane of the equator, as determined by the latitude of the observer.

With the foregoing and other objects in view, I have devised the construction illustrated in the accompanying drawings forming a part of this specification. It is, however, to be understood the invention is not limited to the specific details of construction and arrangement shown, but may embody various changes and modifications within the scope of the invention.

- In these drawings:

FIG. 1 is a view looking toward a sundial constructed according to this invention and mounted at the inner side of a south-facing window;

' FIG. 2 is an elevational view thereof looking from the left of FIG. 1 and showing a portion of the window in section;

FIG. 3 is a transverse section of the form of the device shown in FIG. 1 taken substantially on the line 3-3 of FIG.

FIG. 4 is a side elevation thereof looking toward the translucent dial side of the device;

FIG. 5 is a top plan view with a part of the top wall broken away and a portion of the side wall shown in section;

FIG. 6 is a similar view showing a slight modification;

FIG. 7 is a development of the calibrated dial of the devices of FIGS. 1 to 6;

FIG. 8 is a top plan view of a portion of a modified form of the device adapted for outdoor use;

FIG. 9 is an elevational view looking toward the bottom of FIG. 8, and

FIG. 10 is a side view of the form of the device of FIGS. 8 and 9 on a reduced scale, showing it mounted on a form of supportrwhich may be used for outdoor use as well as on a stand or other support at the inner side of a south-facing window. 7

The form of the device shown in FIGS. 1 to 7 is designed primarily for use by mounting on the inner side of a south-facing glass window, the lower portion of the upper sash of such a window being shown at and a pane of the lower sash shown at 16. This form of the sundial includes a body portion 18 in the form of a ring or sleeve, preferably of transparent plastic, and is provided at its opposite ends with outwardly extending flanges l9 and 20 of the same material. On the side that is to be toward the south when the device is mounted for observing different hours of the day, there are mounted between the flanges opaque blocks 21. These may be of any suitable material, such, for example, as

wood. There are four shown in FIGS. 5 and 6 of the drawing to provide three apertures for passage of beams of sunlight, but different numbers may be employed if found desirable to provide more or a different number of such apertures. The blocks are so mounted that between the edges 22 of adjacent blocks there is left a narrow aperture or slot, indicated at 23 24 and 25, through which ribbons or narrow strips of sunlight may pass. In the form shown there are four of these blocks used and forming between them three of these slots or apertures 23, 24 and 25, located 45 apart and exending longitudinally of the cylindrical wall formed by the blocks 21 and parallel to the aXis of this wall indicated at 33 in FIG. 2. The edges 22 are inclined so that the passage between them is tapered with the edges 22 preferably located at an angle of about 50, tfor a purpose presently to be described.

' On the opposite or north side of the body member, or the side toward the room or the observer, there is mounted a stripof translucent or semi-transparent material 26 covering the surface of the transparent body 18 and extending between the flanges 19 and 20. This provides a dial face opposed to and facing the inner or concave side of the opaque cylindrical wall formed by the blocks 21. This dial face, as shown in FIGS. 4 and 7, is marked with longitudinal lines parallel with the axis of the cylindrical walls and so located as to indicate the positions where the ribbons or narrow strips of sunlight from the slots 23, 24- and 2S impinge on this dial face at successive hours of the day. Thus the broken or dotted lines 8, 9 and 10 are so located as to indicate the time by means of the strip of light passing through the slot 24 in the morning and for the hours eight to ten as indicated; the light solid lines 11, 12 and 1 are located to indicate the three hours eleven to one in the middle of the day by light passing through the slot 23, while the dash-and-dot lines 2, 3 and 4 cooperate with the beam of light passing through the slot 25 to indicate corresponding hours in the afternoon. As the apparent movement of the sun is 15 an hour, these hourly lines would be spaced 15 apart. During a part of the year the narrow light streaks from the slots or apertures 23, 2.4 and 25 will extend on the dial face from the lower to the upper flange. They will be shorter in midwinter and in midsummer due to the change in the declination or elevation of the sun, and therefore in order to insure that there will be some portion of this strip of light impinging on the dial face at all times, the distance between the flanges, or that is, the width or height of the dial face and the diameter of'the cylindrical surfaces are so proportioned that at no time do these narrow strips or ribbons of light fail to reach some part of the dial face.

The opposite ends of the drum or body 18 are closed by disks 27 and 28 of opaque material secured on the flanges 19 and 20. They may be of cardboard or plastic sheet or any other suitable material, and as they are opaque they darken the inside of the drum or cylinder so that the bright lines of sunlight impinging on the dial as are made more conspicuous and more easily distinguishable.

The opaque clocks 21 of the cylindrical wall on the south side are so designed that the angle between their edges 22 of adjacent blocks will be about 50'. With this angle, as the apparent motion of the sun is 15 arr-hour, the ribbon from each slot will appear for a little more than three hours. At the beginning of this time the ribbon of light will appear as a narrow strip or line and gradually increase in width to the full width of the slot at about the mid-part of this time interval and then gradually decrease again in width until it disappears. Thus in the band from line ii it will first appear as a narrow line forwardly of Patented May 1, 1%62" n (a line 11 at about :30, attain full width at the mid-point noon or twelve oclock, and then gradually narrow until it disappears at 1:30, it being cut off bythe side walls 22.

As the portion of the dial face traversed by the ribbon of light from any one slot will overlap to some extent the portion covered by another slot, it might cause confusion if some means were not provided to distinguish between the ribbons of light and the portions of the dial face on which they cooperate with the calibrated lines. Thus colored filters covering all or certain of the slots 23, 24 and may be used. For example, over the slot 24 toward the southeast a red filter may be used, indicated at 29, such as a strip of red transparent plastic. Through the slot 23 facing to the direct south, white light may be ob lowed to pass, and over the slot 25 to the southwest a blue filter may be used. The particular colors chosen are not important, as the important feature is that colors for the diiferent slots be sufliciently different so that the ribbon or lineof light passing through them to the dial face be sufiiciently ditferent to be readily distinguishable. Also, to assist in readily distinguishing from the indications of the diiierent slots, the lines 8, 9 and 16 over which the beam from the slot 24 having the red filter is directed may be colored red. Similarly, the'lines ll, 12 and i may be white or yellow lines or in some other way distingmisbed. This is done by using solid light lines on the drawing, and for the beam from the slot 25 through the blue filter 38 the dot-and-dash lines indicated by 2, 3 and 4 may be blue lines;

Simple and eifective means is shown in FIGS. 1 and 2 for mounting the sundial shown in FIGS. 1 to 7', at the inner side of the south-facing glass window and properly oriented for correct indication of time with its axis practically parallel to the axis of the earth and its end Walls parallel to the plane of the equator. For this purpose the flanges 19 and 20, including the end disks 2'7 and 28, are provided with a series of openings 31 preferably located 45' apart. A thread loop 32 is fastened to the lower flange 20 by passing it through the east and west openings 31 at the sidesindicated at E and W in FIG. 5, and extended around the body of the dial 26, as shown in PEG. 2, and its free end portion 32a secured to the inner side of the glass 16 by a suitable adhesive, such as a piece of Scotch Tape 33, with the upper edge of the lower flange against the surface of the glass. Another thread loop 34 is passed through similarly located openings 31 in the upper flange 19 and about the northern side or dial 25, as also shown in FIG. 2, with its free end 340 secured to a ring; 35. Attached to this ring are two threads as that extend outwardly about 45 apart, and at their upper ends may be secured to the window sash at laterally spaced points by the adhesive means 37 after the proper position of the sundial has been determined. By means of these threads the sundial is readily swung into the plane of the meridian and tilted upward from the plane of the horizon the same number of degrees as the latitude of the locality of the observer to locate its axis 38 parallel to the axis of the earth and its opposite ends parallel to the plane of the equator. Thus the axis 38 of the sundial is inclined to the horizontal 39 at an angle 40 corresponding to the degree of latitude of the location at which the sundial is being used, or the inclination of the end flange and disk 28 may be tilted to the plane of the window glass by the same angle 41. This setting may be accomplished by a protractor or other similar device, and when thus properly oriented the upper ends of the cords or threads 36 may be secured to the sash by the adhesive means 37. The sundial may be, left in this position indefinitely, and as an astronomical instrument in this position is said to be equatorially mounted. As the opposite ends of the sun dial rest in the thread loops 32 and 3d at the inner sides of the flanges 19 and 20, if the sundial is lifted slightly it can be turned in these loops so that the readings on the dial face with the corresponding light beam will be in accord with clock time, and then released so as to be 4; allowed to rest on the loops where it will be held in place by friction to indicate correct time.

This adjustment to clock time (mean solar time) may have to be made about once a month. Also by this slight turning of the sundial compensation is made for its position in the time zone for changing length of the solar day (equation of time) and for Daylight Saving Time. 7

It will be noted the description and orientation or the sundial as described above apply to its use in the Northern Hemisphere. For use in the Southern Hemisphere the indications of the points of the compass would be reversed.

In FIG. 5 the sides 22 of the tapered apertures in the southern opaque cylindrical wall are arranged so that the narrowest part is at the outer or convex side of the wall, but the same efiect can be secured by reversing this arrangement, as shown in H6. 6, with the edge walls 22a of blocks 21a so arranged as to bring the narrowest part of the aperture or the light slots 23a, 24a and 25a, corresponding to slots 23, 24 and 25, at the inner or concave side of this wall.

FIGS. 8, 9 and 10 indicate how this type of sundial may be employed in larger sizes for outdoor use, although it is not limited to such use, but may be used at the inner side of a south-facing window on a stand or other suitable support. In this form as shown it comprises a lower disk 42 forming a dial provided with a dial face calibrated with the lines 8 to 12 and 1 to 4 for the hours of the day. The opaque cylindrical wall corresponding to the wall formed by blocks 21 in the first form of FIGS. 1 to 7, is formed by the four blocks 43 spaced to provide the narrow longitudinally extending slots 23, 24 and 25 corresponding to the slots as shown in FIGS. 1 to 7. Although the outer and inner walls of the blocks 43 are shown as being fiat or straight, when assembled they in effect form a cylindrical wall with the slots 23, 24 and 25 on the surface of this wall, the same as would be the effect if these blocks were curved. These blocks may be wooden blocks mounted at their lower ends on the dial 42 and with their tapered edges 22 spaced properly to provide the narrow slots 23, 24 and 25, apart on the surface of the cylindrical wall, and these edges are tapered or inclined so that when the blocks are in place the sides of the apertures for passage of the ribbons of light are at an angle of about the same as the apertures in the first form. The tops of the blocks may be covered and secured together by a curved cover plate 44 which. may be of a length and Width depending on how much it is desired to cover and enclose the .dial face of the dial 42. For ordinary purposes these blocks 43 are about three inches high for a dial 42 of eight inches diameter, and the cover 44 is also about three inches wide and extending to adjacent the ends of the outer blocks.

To distinguish between the ribbons of sunlight passing through the narrow slots 23, 24 and 25, they may be covered with transparent colored filters, the same as described for the slots in the first form. Thus, the slot 24 may be covered with a red filter 45 and the slot 25 covered with a blue filter 46. Similarly the lines 8, 9 and 10 shown as dotted lines to indicate that they may be of the color red correspond with the filter 45 and indicate they are to be read with the red beam of light passing through the slot 24 to indicate the corresponding hours of the day. Similarly, the light solid lines 11, 12 and 1 may be white or yellow, or if made solid as in the drawing, could be black lines for cooperating with the ribbon of light through the slots 23 to indicate the corresponding hours, and the dot-and-dash lines 2, 3 and 4 may be blue lines to correspond with the light passing through the slot 25 to indicate that they are to be read with this colored light beam. For indicating hourly intervals the lines would be separated by 15 angles.

It will be seen that although the dial 42 and its calibrated face com-prises a fiat disk, still it is opposed to the opaque cylindrical wall provided with the slots 23, 24 and 25, and is located on the inner or concave side of this wall, the same as is the cylindrical dial 26 of the first form, and cooperates with the narrow ribbons or strips of sunlight passing through the narrow slots in the south wall to indicate the hours of the day, the same as in the first form.

It is mounted so that it can be oriented with relation to the plane of the meridian, or that is, with the axis of the cylindrical wall parallel to the earths axis, and the plane of the dial 42 parallel to the plane of the equator. In other words, this device may be equatorially mounted the same as the first form. For this purpose it is mounted on a block 47 hinged to a base 48 at its lower end, as indicated at 49, the disk forming the dial 42 being secured to the support 47 by a suitable bolt 50 at its center. The disk with the cylindrical wall mounted by the blocks 43 may thus be adjusted at different angular positions about this bolt and then clamped in adjusted position. For accomplishing this the dial 42 is provided with extensions 51 at opposite sides provided with curved slots 52 struck about the center and through which are bolts having wing nuts 53 which may be loosened to permit adjustment of the device and then tightened to secure it in the adjusted position. The block 47 may be adjusted to different angular positions and secured therein by curved strips 54 secured to the base 48 and, provided with curved slots 55 struck about the hinge 49 as the center, with bolts having wing nuts passin through this slot by which the block 47 may be mounted in its adjusted position. Thus with the base 48 level and in the north and south position with the axis 57 in the plane of the meridian the hinge 49 will be in the east-west position. Then the block 47 may be adjusted to the angle 56 corresponding to 90 minus the latitude of the position of the observer, thus bringing the axis 57 of the sundial parallel to the axis of the earth and the plane of the dial 42 parallel to the plane of the equator. After the dial is positioned with its axis in the plane of the meridian and the block 47 adjusted to the proper angle, the dial 42 with the cylindrical wall formed with the light slots may be adjusted about its pivotal center 50 and set by a clock to indicate the proper time by cooperation of the light beams passing through the slots 23, 24 and cooperating with the calibrations on the dial face 4-2, the same as described in connection with the first form.

It will thus be seen the device provides a simple and effective sundial which may be readily mounted and adjusted to indicate accurate clock time. As the use of the plurality of slots for passage of the strips of sunlight in the south cylindrical wall does not depend on a single slot for indicating the hours throughout the day, but by using a plurality of slots spaced the proper distance apart, preferably 45, each slot may be used for indicating time only for a portion of the day and thus will function more accurately than would be a single slot if used for indicating time throughout the whole day. Also, by using the different colored filters for the different light slots, the beams of sunlight passing through these slots and impinging on the corresponding portions of the dial face can be readily distinguished so that the more accurate readings thus secured can also be readily distinguished.

Having thus set forth the nature of my invention, I claim:

1. A sundial comprising a cylindrical wall provided with spaced longitudinal narrow slots for passage of narrow beams of sunlight, means providing a dial face at the.

inner side of said wall on which said beams of light may impinge, said dial face being calibrated to indicate different hours of the day by the positions of said beams, and means for mounting the sundial with the axis of said wall parallel to the axis of the earth and its convex side facing the sun.

2. A sundial comprising a cylindrical wall provided with a plurality of laterally spaced longitudinal narrow slots covered with different colored light filters for passage of sunlight, means providing a dial face at the concave side of said wall in position for the light beams from said slots to impinge, said dial face calibrated to indicate different hours of the day by the positions of said beams, and means for supporting the sundial with the axis of said wall parallel to the earths axis and the convex side of said wall facing south.

3. A sundial comprising a cylindrical wall provided with a plurality of laterally spaced longitudinal slots therethrough for passage of beams of sunlight, said slots tapering in width from one side of said wall to the other providing a narrow slot at one side, and side walls limiting the lateral angle from which direct sunlight will pass through the slots, means providing a dial face at the concave side of said wall in position for the light beams from said slots to impinge and calibrated to indicate different hours of the day by the positions of said beams, and means for supporting said wall with its convex side facing south and its axis parallel to the earths axis.

4. A sundial comprising a cylindrical wall provided with a plurality of laterally spaced longitudinal narrow slots for passage of narrow beams of sunlight, means at the concave side of said wall providing a dial face facing said Wall on which beams of sunlight through the slots may impinge, means for orienting the sundial at the inner side of a south-facing glass window with the edge of the lower end of said wall against the glass and its axis inclined parallel to the earths axis comprising a loop of thread fastened to each end of said wall and each having a free end, means for fastening the free end of the lower loop to the glass, and a thread secured to the free end of the upper loop with means for fastening said latter thread to the window at laterally spaced points above the sundial.

5. A sundial comprising a cylindrical body portion provided with laterally extending flanges at its opposite ends, one side portion of said body portion provided with a plurality of laterally spaced longitudinal narrow slots for passage of narrow bands of direct sunlight, the opposite side of said body portion facing the first portion of translucent material providing a dial face having longitudinal lines adapted to cooperate with said bands to indicate the hours of the day, said flanges provided with holes therethrough on opposite sides of the body portion, and means for supporting and orienting the sundial at the inner side of a south-facing glass window.

6. A sundial comprising a cylindrical wall provided with a plurality of laterally spaced longitudinal narrow slots covered with different colored light filters for passage of sunlight, means providing a dial. face at the concave side of said wall in position for the light beams from said slots to impinge, said dial face provided with a set of calibrations arranged to cooperate with the beam of sunlight from each slot to indicate hours of the day and each set of calibrations colored to correspond with that of the light filter of the associated slot, and means for supporting the sundial with the axis of said wall parallel to the earths axis and the convex. side of said wall facing south.

7. A sundial comprising a cylindrical body portion of transparent material provided with laterally extending flanges at its opposite ends, a series of opaque blocks mounted on one side of said body between the flanges and separated at their adjacent edges providing a plurality of circumferentially spaced narrow longitudinal slots for passage of direct sunlight, different colored transparent filters over said slots, the opposite side portion of said body from said slots covered with translucent material provided with a set of calibrations to cooperate with the beam of sunlight from each slot to indicate hours of the day and each set of calibrations colored to correspond with that of the light filter of the associated slot, and means for supporting the body with the slots 7 facing toward the sun and its axis parallel with the earths axis.

8. A sundial comprising a flat disk providing a dial face, a series of opaque blocks mounted on the top surface at one side thereof providing a cylindrical wall, said blocks being spaced at their adjacent edges providing a plurality of laterally spaced longitudinal narrow slots for passage of beams of direct sunlight to said dial face, dilterently colored light filters over said slots, a set of calibration lines on the dial face leading from each slot and located to cooperate with the. light beam of said slot to indicate hours of the day, a supporting base, a supporting block hinged at one end edge to the base,

References (Jited in the file of this patent UNITED STATES PATENTS 648,770 Miller May 1, 1900 2,207,195 Guadet July 9, 1940 2,931,102 TheW Apr. 5, 1960 

